In order to solve the problem, various types of heat recovery ventilation apparatuses have been proposed. The ventilation apparatuses are typically classified into rotary-type ventilation apparatuses, heat pipe-type ventilation apparatuses, and plate-type ventilation apparatuses. The heat pipe-type ventilation apparatuses use a refrigerant, such as Freon, so that they are suitable for large-scale facilities, such as buildings. However, the heat pipe-type ventilation apparatuses are disadvantageous in that a heavy burden of expense for installation and maintenance is incurred. The plate-type ventilation apparatuses are suitable for air conditioners. However, the plate-type ventilation apparatuses are disadvantageous in that it is very inconvenient to clean a large number of cooling fins provided in the ventilation apparatuses and maintain the performance of the ventilation apparatuses. The rotary-type ventilation apparatuses are relatively small in processing capacity thereof but are simple in structure. Thus, the rotary-type ventilation apparatuses are suitable for small-scale facilities, for example, homes, offices, barns, greenhouses, mushroom culture boxes, and earthworm cages.
However, there has been increased demand for novel heat recovery ventilation apparatuses, which have heating, cooling, and dehumidifying functions according to seasons, and which filter external dangerous materials, thus maintaining clean indoor air, in addition to recovering waste heat regardless of whether they are used residentially or industrially.